Circular heat exchangers have been employed in a wide range of applications such as for condensers for refrigerators and air conditioners as well as for radiators for cooling internal engines and power transmission. Examples of such constructions are disclosed in U.S. Pat. Nos. 2,029,891 (Condenser For Refrigerator), 4,062,401 (Radiator For Engine Transmission And Hydraulic Accessories), 4,202,296 and 4,510,991 (Radiator For Cooling Internal Combustion Engines). Such heat exchangers are, in general, complex and costly and their use is restricted since they require numerous special components and in particular many require specialized corrugated fins or air centers used to support the heat exchanger tubes and to effectively increase the external surface area for enhancing heat transfer. Generally these centers are made from corrugated strips of the heat conducting metal which are brazed or otherwise secured at their apecies or peaks to adjacent sides of any two tubes. In the event that the tubes are arcuately spaced and have a rectilinear form, the air centers need to be tapered or otherwise formed to provide the necessary contact along the width and length of adjacent tubes for optimizing heat conducting therefor efficiency. Such air centers are not market available and are difficult to manufacture particularly as compared to conventional rectilinear corrugated air centers which have constant convolution height and width throughout their lengths.